MAPC-50

Boom! The classic potato gun harnesses the combustion of flammable vapor. Show us your combustion spud gun and discuss fuels, ratios, safety, ignition systems, tools, and more.
Killjoy
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Sat Nov 18, 2006 3:07 am

MAPC-50
(Mobile Assault Potato Cannon- 50 millimeter)

I orignally built this cannon for a friend of mine for his birthday, but his mom didnt like the idea so I ended up keeping it. Because Im a cheap bastered, I didnt want to use any of my 4" diameter pvc pipe ( had a hell of a time trying to find it to began with). So I decided to use a plastic soda bottle. I had used bottles in several of cannons as the combustion chamber with great success but I wanted this one to be different. Also I knew this was a cheap way to have a clear combution chamber.

To began with, I cut of the end of a 2 liter coke bottle and then used a blow torch to get the bottle to shrink around a 3" end cap. I then screwed it on to the cap with 10 screws and then tightened one of those pipe clamp things around it just to be sure it would'nt break. After that I drilled a hole big enough to fit a 2" female threaded adaptor in and epoxied it in with Plastic Bond (I think its called that) which has a holding strength of 2500 lbs. Next I used a 1" to 2" adaptor with a 2" male threaded adpator on the end and gorilla glued the screw top of the bottle in to the 1" part of the adaptor and then bolted that in to make sure it wouldn't blow off. after that I added a propane meter and then mounted a camera flash igniton circuit in a little black box with a toggle switch with a flip cover so the capacitor will only be charged when I need it so I will be less likely to elctrocute myself. I also added a chamber fan which is turned on or off by the red rocker switch. Finnaly I cut a carry handle (it was original going to be shoulder mounted but that seemed like a bad idea) out of 1/2 inch ply wood, sprayed painted it matt black, and then mounted the trigger switch (mometary pushbutton). I attach a 2' long 2" diameter barrel by a threaded female adaptor.

Now before you guys get all work up about how the thing is going to break or blow up because of the connection between the end cap and bottle, I've tested the cannon over 50 times, 25 of which where remote triggered and never have any sign of weakness from any part of the cannon. I also first pressurized it with compressed air to about 125 psi and only had a slight leak from the hole where the wires entered for the chamber fan. I have concluded that this cannon is completly safe (as safe as something which is containing hot gases and propels a projectile at several hundred feet per second can be lol)

The Cannon
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The main components of the cannon.
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The left side of the cannon, you can also see how I connected the bottle to the end cap
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The spark gap
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A piece of wood after having a couple chunks blown out of it by golfballs at about 35 feet away.
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experament_u2
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Sat Nov 18, 2006 3:47 am

ARE U SERIOUS THAT IS AWSOME all that mad crap and its got a soda botle chamber im begining to like u thats a good looking gun

btw wat size in mm is ur barel

great gun 8)
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CS
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Sat Nov 18, 2006 4:18 am

I fixed your post as it was previously a large mass of endless text.

Nice gun! As the above user noted, what a cannon to make while first starting with a clear soda bottle. Ignition system is really nice looking. I just like how ever thing required for the gun is contained and onboard the launcher.

Something I just noticed, it appears that the modded torch valve is cross threaded onto the propane tank...
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Pyro Ninja
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Sat Nov 18, 2006 4:38 am

I like it
Pretty cool...................................... :)
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noname
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Sat Nov 18, 2006 11:22 am

You're a cheap bastard, yet you'd make your friend a propane metered combustion cannon with stungun ignition? Nice anyways.
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schmanman
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Sat Nov 18, 2006 11:37 am

I like it. the 2-liter bottle as the chamber is pretty common, but the way you did it, I haven't seen it before. good job.Image
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Killjoy
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Sat Nov 18, 2006 3:21 pm

pimpmann22 wrote: Something I just noticed, it appears that the modded torch valve is cross threaded onto the propane tank...
yeah i just got the torch valve to stay on the tank for a picture (never screwed it on), but it screws on normally.
the barrel is 2" in diam which means it is a little more then 50 mm in diameter.
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frankrede
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Sat Nov 18, 2006 5:22 pm

schmanman wrote:I like it. the 2-liter bottle as the chamber is pretty common, but the way you did it, I haven't seen it before. good job.Image
Hmm, I usually only see it on pneumatics, all in all, that is an amazing cannon.
Do you ever have problems with The plasic warping from teh heat?
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Killjoy
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Sat Nov 18, 2006 6:38 pm

No, actually the bottle had all these dents in it before i evr fired it, but after a couple of fireings the dents popped out. i also dont fire more then 3 shots in a row because i want to let it cool down. also the fan helps to cool the bottle.
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MisterSteve124
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Sat Nov 18, 2006 7:12 pm

That is the nicest cannon i have ever seen using a soda bottle chamber. Good job! What do you use to know how much propane ur using? I don't see a reg or a gauge.
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killagorrila99
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Sat Nov 18, 2006 10:23 pm

Been there, Done that, Bought the T-shirt.

I still like it though.
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Killjoy
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Sun Nov 19, 2006 2:33 am

I just hit home depot this morning and picked up a pressure regulator with a guage so no more guessing. Before I was kinda guessing at how much i was using which still worked.
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schmanman
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Sun Nov 19, 2006 9:02 am

yes, It is used on pneumatics, but I've also seen them used on combustions with small bore barrels.
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sgort87
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Wed Nov 22, 2006 6:13 pm

Nice dude!

I proudly present Killjoy with the coveted <a href="http://www.geocities.com/sgort87/ghetto">Ghetto Award
</a> for his ingenious use of a pop bottle.
Last edited by sgort87 on Thu Nov 23, 2006 4:19 am, edited 1 time in total.
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nicholai
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Wed Nov 22, 2006 6:35 pm

lmao... gort thats a funny "ghetto award" picture. I laughed so hard i spit my beer out when i first saw it.

oh, you forgot a quote at the end of the html tag "
Last edited by nicholai on Wed Nov 22, 2006 7:00 pm, edited 1 time in total.
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